Predictive Lagrangian Optimization for Constrained Reinforcement Learning

Fuente: arXiv
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Autores principales: Zhang, Tianqi, Yuan, Puzhen, Zhan, Guojian, Lin, Ziyu, Lyu, Yao, Qin, Zhenzhi, Duan, Jingliang, Zhang, Liping, Li, Shengbo Eben
Formato: Preprint
Publicado: 2025
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author Zhang, Tianqi
Yuan, Puzhen
Zhan, Guojian
Lin, Ziyu
Lyu, Yao
Qin, Zhenzhi
Duan, Jingliang
Zhang, Liping
Li, Shengbo Eben
author_facet Zhang, Tianqi
Yuan, Puzhen
Zhan, Guojian
Lin, Ziyu
Lyu, Yao
Qin, Zhenzhi
Duan, Jingliang
Zhang, Liping
Li, Shengbo Eben
contents Constrained optimization is popularly seen in reinforcement learning for addressing complex control tasks. From the perspective of dynamic system, iteratively solving a constrained optimization problem can be framed as the temporal evolution of a feedback control system. Classical constrained optimization methods, such as penalty and Lagrangian approaches, inherently use proportional and integral feedback controllers. In this paper, we propose a more generic equivalence framework to build the connection between constrained optimization and feedback control system, for the purpose of developing more effective constrained RL algorithms. Firstly, we define that each step of the system evolution determines the Lagrange multiplier by solving a multiplier feedback optimal control problem (MFOCP). In this problem, the control input is multiplier, the state is policy parameters, the dynamics is described by policy gradient descent, and the objective is to minimize constraint violations. Then, we introduce a multiplier guided policy learning (MGPL) module to perform policy parameters updating. And we prove that the resulting optimal policy, achieved through alternating MFOCP and MGPL, aligns with the solution of the primal constrained RL problem, thereby establishing our equivalence framework. Furthermore, we point out that the existing PID Lagrangian is merely one special case within our framework that utilizes a PID controller. We also accommodate the integration of other various feedback controllers, thereby facilitating the development of new algorithms. As a representative, we employ model predictive control (MPC) as the feedback controller and consequently propose a new algorithm called predictive Lagrangian optimization (PLO). Numerical experiments demonstrate its superiority over the PID Lagrangian method, achieving a larger feasible region up to 7.2% and a comparable average reward.
format Preprint
id arxiv_https___arxiv_org_abs_2501_15217
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Predictive Lagrangian Optimization for Constrained Reinforcement Learning
Zhang, Tianqi
Yuan, Puzhen
Zhan, Guojian
Lin, Ziyu
Lyu, Yao
Qin, Zhenzhi
Duan, Jingliang
Zhang, Liping
Li, Shengbo Eben
Machine Learning
Systems and Control
Constrained optimization is popularly seen in reinforcement learning for addressing complex control tasks. From the perspective of dynamic system, iteratively solving a constrained optimization problem can be framed as the temporal evolution of a feedback control system. Classical constrained optimization methods, such as penalty and Lagrangian approaches, inherently use proportional and integral feedback controllers. In this paper, we propose a more generic equivalence framework to build the connection between constrained optimization and feedback control system, for the purpose of developing more effective constrained RL algorithms. Firstly, we define that each step of the system evolution determines the Lagrange multiplier by solving a multiplier feedback optimal control problem (MFOCP). In this problem, the control input is multiplier, the state is policy parameters, the dynamics is described by policy gradient descent, and the objective is to minimize constraint violations. Then, we introduce a multiplier guided policy learning (MGPL) module to perform policy parameters updating. And we prove that the resulting optimal policy, achieved through alternating MFOCP and MGPL, aligns with the solution of the primal constrained RL problem, thereby establishing our equivalence framework. Furthermore, we point out that the existing PID Lagrangian is merely one special case within our framework that utilizes a PID controller. We also accommodate the integration of other various feedback controllers, thereby facilitating the development of new algorithms. As a representative, we employ model predictive control (MPC) as the feedback controller and consequently propose a new algorithm called predictive Lagrangian optimization (PLO). Numerical experiments demonstrate its superiority over the PID Lagrangian method, achieving a larger feasible region up to 7.2% and a comparable average reward.
title Predictive Lagrangian Optimization for Constrained Reinforcement Learning
topic Machine Learning
Systems and Control
url https://arxiv.org/abs/2501.15217